WOLFRAM

Wolfram Language & System Documentation Center
Wolfram Language Home Page »
RLink`
RLink`

REvaluate

REvaluate[code]

evaluates a string of R code, and returns the result as a Wolfram Language expression.

Details and Options

  • The code code must be a string of valid R code, which, after execution, produces the result of one of the types that can be handled by REvaluate.
  • These are the R types explicitly supported by RLink, elements of which can be returned by REvaluate, along with the internal RLink heads of expressions representing such elements:
  • "integer"RVector
    "double"RVector
    "complex"RVector
    "logical"RVector
    "character"RVector
    "list"RList
    "NULL"RNull
    "closure"RFunction
    "builtin"RFunction
    "environment"REnvironment
  • Apart from explicitly supported types, most other types can be imported from R into the Wolfram Language by converting them into a string (deparsed R code). Such elements are wrapped into an RCode wrapper.
  • The type "environment" is only partially supported at present. Namely, it will consider all environment objects explicitly exported from R into the Wolfram Language to represent global environments.
  • When the code passed to REvaluate evaluates to a type not handled by REvaluate, REvaluate returns $Failed.

Examples

open allclose all

Basic Examples  (12)Summary of the most common use cases

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-h8fcah

This constructs a list (R vector) of 10 consecutive integers:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-bpfv27
Out[1]=1

This uses a general vector constructor in R to construct a vector of numbers:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-e2ka7m
Out[1]=1

To suppress the output, or when no output is needed, put a semicolon at the end of the R code, in which case REvaluate returns Null:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-iesvg8

When scalars are entered, they are automatically considered vectors of length 1 by R. This is reflected in RLink:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-cwi4x7
Out[1]=1

By default, real numeric quantities are interpreted as doubles:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-cfoa29
Out[2]=2

One way to have R interpret them as integers is to use R's as.integer function:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-c688tp
Out[3]=3

This returns a more general sequence:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-fr6qf2
Out[1]=1

The Wolfram Language's equivalent follows:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-hworz9
Out[2]=2

This computes the sine function on the sequence from the previous example (most functions in R are vectorized, just as in the Wolfram Language):

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-ez126m
Out[1]=1

This is the same, but using explicit function mapping (sapply in R corresponds to Map in the Wolfram Language):

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-ehidlp
Out[2]=2

The second method is slower, however, just as it would be in the Wolfram Language:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-f27tzk
Out[3]=3
Out[3]=3

This is a slightly more complex example. Here, a function is mapped that takes a value of the independent variable and returns it back together with the value of the function (here, sine) wrapped in a vector:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-d8bgcc
Out[1]=1

Here is the Wolfram Language's equivalent for the rhs of the assignment from the previous example:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-dbryvu
Out[2]=2

You can use larger pieces of R code inside REvaluate. In such a case, however, you should wrap your statements in a block (curly braces):

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-ec8zj8
Out[1]=1

This splits a string, and actually returns a list rather than a vector, which is reflected in extra curly braces:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-diux3p
Out[1]=1

Note that you have to escape the quotation marks.

This generates a random 5×5 matrix:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-c6qd4u
Out[1]=1

This computes eigenvalues and eigenvectors:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-b98aac
Out[2]=2

You can see that the result is an R list and has a non-empty attribute set (attribute names); therefore, it is represented as a general R object with a head RObject. This topic is covered in more details in "R Data Types in RLink" and the RObject reference page.

This extracts only eigenvectors:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-j34l5b
Out[3]=3

Or eigenvalues:

In[4]:=4
✖
https://wolfram.com/xid/0ptseqibvvfwq8-dcenle
Out[4]=4

This is the same in the Wolfram Language (eigenvectors do not necessarily have to be the same in this case):

In[5]:=5
✖
https://wolfram.com/xid/0ptseqibvvfwq8-eow0cq
Out[5]=5

This creates a random matrix in the Wolfram Language:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-g00o0z
Out[1]=1

Send it to R:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-k3mubb
Out[2]=2

The result of this element-wise logical comparison is a logical vector (matrix):

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-bad11i
Out[3]=3

Test that the result is of a logical type:

In[4]:=4
✖
https://wolfram.com/xid/0ptseqibvvfwq8-ga1yrh
Out[4]=4

This lists the current objects present in your R workspace:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-g0io4d
Out[1]=1

Scope  (8)Survey of the scope of standard use cases

Assignments  (3)

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-pwbj4z

You can also use REvaluate to make assignments. So you can, for example, do the following assignment to a global variable myint in the R workspace:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-birx2d
Out[2]=2

REvaluate can now be used to check the content of the newly created global variable myint:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-epoetm
Out[3]=3

The following assignment will return a function reference:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-bju2ue
Out[1]=1

It may be used either on the R side (since this function was given a name in R):

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-bl1t11
Out[2]=2

Or on the Wolfram Language side:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-5gadh
Out[3]=3

To make assignments but suppress returning the result back to the Wolfram Language, you can suppress the output by adding a semicolon at the end:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-krcu4u
In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-hllfdm
Out[2]=2

Multidimensional Arrays  (3)

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-fbrmw

While you can handle multidimensional arrays with REvaluate just as easily as one-dimensional arrays, there are a few subtleties.

This will create a random one-dimensional array in R:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-dqlp70
Out[2]=2

Since R stores arrays in column-major order, the previous result is not what you might have expected. But this is needed for consistency regarding array indexing:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-qyecw
Out[3]=3
In[4]:=4
✖
https://wolfram.com/xid/0ptseqibvvfwq8-b7bakd
Out[4]=4
In[5]:=5
✖
https://wolfram.com/xid/0ptseqibvvfwq8-ile3tx
Out[5]=5
In[6]:=6
✖
https://wolfram.com/xid/0ptseqibvvfwq8-d8ayvb
Out[6]=6

To convert the array to row-major order (which is the order used by the Wolfram Language), you can use Transpose:

In[7]:=7
✖
https://wolfram.com/xid/0ptseqibvvfwq8-jy26cp

For example:

In[8]:=8
✖
https://wolfram.com/xid/0ptseqibvvfwq8-jbgw22
Out[8]=8

The dimensions get reversed:

In[9]:=9
✖
https://wolfram.com/xid/0ptseqibvvfwq8-db7v87
Out[9]=9

And the same for indexing for the converted array:

In[10]:=10
✖
https://wolfram.com/xid/0ptseqibvvfwq8-tcj6h
Out[10]=10
In[11]:=11
✖
https://wolfram.com/xid/0ptseqibvvfwq8-cyz0u8
Out[11]=11

The above issues only show up for arrays created in R and then sent to the Wolfram Language. If you create an array in the Wolfram Language and then send it to R, it is automatically transformed to column-major order, and back to row-major order when you get it back from R. Therefore, in such cases, you get back the original array.

This creates an array in the Wolfram Language:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-emx29y
Out[1]=1

Send it to R:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-e11vzk

And get it from R:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-gl68jc
Out[3]=3

As before, the indexing is consistent with that in the Wolfram Language:

In[4]:=4
✖
https://wolfram.com/xid/0ptseqibvvfwq8-bbgcpr
Out[4]=4
In[5]:=5
✖
https://wolfram.com/xid/0ptseqibvvfwq8-eqjdzj
Out[5]=5

This means that you can send Wolfram Language arrays to R and continue working with them in R, just like you would in the Wolfram Language.

As another example, consider matrix multiplication. First, construct a matrix in the Wolfram Language:

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-irr1i2
Out[1]=1

Now send it to R, assigning it to a variable mmat in the R workspace:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-moy9np
Out[2]=2

This will perform the matrix multiplication:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-fcnzen
Out[3]=3

It yields the same result as it would in the Wolfram Language:

In[4]:=4
✖
https://wolfram.com/xid/0ptseqibvvfwq8-bo65d7
Out[4]=4

Special Quantities: NaNs and Infinities  (1)

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-cq6n6e

There is currently a one-directional support for special quantities such as NaNs and infinities of various kinds.

The following R input demonstrates how various quantities are translated into the Wolfram Language. This is what you would get directly in the R console:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-nx1pf
Out[2]=2

And in the Wolfram Language:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-dax8sk
Out[3]=3

In order to get a complex result when taking a square root of a negative number, that number must be entered manifestly as a complex number:

In[4]:=4
✖
https://wolfram.com/xid/0ptseqibvvfwq8-bdjgm7
Out[4]=4

While getting such quantities from R to the Wolfram Language is supported, the reverse is currently not:

In[5]:=5
✖
https://wolfram.com/xid/0ptseqibvvfwq8-cse1a
Out[5]=5

Missing Points  (1)

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-gs5xx6

Vectors and lists in R support missing points. In the Wolfram Language, such points are represented by Missing[].

Here is a typical example for a vector:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-c5mu02
Out[2]=2

And a list:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-nlaj5c
Out[3]=3

The action of most functions on missing elements is to produce another missing element. For example:

In[4]:=4
✖
https://wolfram.com/xid/0ptseqibvvfwq8-mfv28d
Out[4]=4

Missing points have a bidirectional support in RLink. For example, the following performs the same computation as the previous example, but with the data sent to R from the Wolfram Language:

In[5]:=5
✖
https://wolfram.com/xid/0ptseqibvvfwq8-ho0zdx
Out[5]=5

For a number of reasons described in the tutorial "Functions" on R functions, the following syntax is much preferred:

In[6]:=6
✖
https://wolfram.com/xid/0ptseqibvvfwq8-jgnsn9
Out[6]=6

Generalizations & Extensions  (2)Generalized and extended use cases

Defining Your Own Functions  (1)

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-g1i4kx

Here is an example of one possible implementation of the Wolfram Language Tuples function in R, returning tuples as data frames:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-cbnw52

Here is how it can be used:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-e5f3k7
Out[3]=3

Manipulating R Objects' Attributes on the R Side, and General R Objects   (1)

In[1]:=1
✖
https://wolfram.com/xid/0ptseqibvvfwq8-boecld

All objects in R can have one or several attributes. In RLink, R objects with generic attributes are represented on the Wolfram side by Wolfram Language expressions with the head RObject. Some aspects of this also affect REvaluate.

The following will construct a matrix in the Wolfram Language, send it to R, and assign it to a variable myInt in the R workspace:

In[2]:=2
✖
https://wolfram.com/xid/0ptseqibvvfwq8-b7zuzj
Out[2]=2

You can inspect the class of the resulting R object stored in a variable:

In[3]:=3
✖
https://wolfram.com/xid/0ptseqibvvfwq8-baehn2
Out[3]=3

Attributes of any R object are stored in an R list. Objects of the class matrix have at least one attribute, "dim", which stores the information about dimensions (dimensions themselves are represented as an integer vector):

In[4]:=4
✖
https://wolfram.com/xid/0ptseqibvvfwq8-d6xitv
Out[4]=4

You can see that this list itself has attributes, in particular the attribute "names", and therefore it cannot be represented as just a Wolfram Language list, but has a head RObject. One shortcut to retrieve the value of a given attribute is to use the R attr function:

In[5]:=5
✖
https://wolfram.com/xid/0ptseqibvvfwq8-fq8zzv
Out[5]=5

You can use REvaluate to perform non-trivial reshaping of your matrix on the R side by modifying its dim attribute. For example, you may convert the matrix into a three-dimensional array with dimensions {2,5,2}:

In[6]:=6
✖
https://wolfram.com/xid/0ptseqibvvfwq8-b1bu0x
Out[6]=6

Which results in the following:

In[7]:=7
✖
https://wolfram.com/xid/0ptseqibvvfwq8-hjbs55
Out[7]=7

At some point, you may wish to add some new attributes to myInt, for example:

In[8]:=8
✖
https://wolfram.com/xid/0ptseqibvvfwq8-fj3ikt
Out[8]=8

And now:

In[9]:=9
✖
https://wolfram.com/xid/0ptseqibvvfwq8-7mlhq
Out[9]=9

The dim attribute is implicit. You can always use RObject-based general representation, even for objects with no attributes:

In[10]:=10
✖
https://wolfram.com/xid/0ptseqibvvfwq8-fd6gzx
Out[10]=10
Wolfram Research (2012), REvaluate, Wolfram Language function, https://reference.wolfram.com/language/RLink/ref/REvaluate.html.
✖
Wolfram Research (2012), REvaluate, Wolfram Language function, https://reference.wolfram.com/language/RLink/ref/REvaluate.html.

Text

Wolfram Research (2012), REvaluate, Wolfram Language function, https://reference.wolfram.com/language/RLink/ref/REvaluate.html.

✖
Wolfram Research (2012), REvaluate, Wolfram Language function, https://reference.wolfram.com/language/RLink/ref/REvaluate.html.

CMS

Wolfram Language. 2012. "REvaluate." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/RLink/ref/REvaluate.html.

✖
Wolfram Language. 2012. "REvaluate." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/RLink/ref/REvaluate.html.

APA

Wolfram Language. (2012). REvaluate. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/RLink/ref/REvaluate.html

✖
Wolfram Language. (2012). REvaluate. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/RLink/ref/REvaluate.html

BibTeX

@misc{reference.wolfram_2024_revaluate, author="Wolfram Research", title="{REvaluate}", year="2012", howpublished="\url{https://reference.wolfram.com/language/RLink/ref/REvaluate.html}", note=[Accessed: 22-June-2025 ]}

✖
@misc{reference.wolfram_2024_revaluate, author="Wolfram Research", title="{REvaluate}", year="2012", howpublished="\url{https://reference.wolfram.com/language/RLink/ref/REvaluate.html}", note=[Accessed: 22-June-2025 ]}

BibLaTeX

@online{reference.wolfram_2024_revaluate, organization={Wolfram Research}, title={REvaluate}, year={2012}, url={https://reference.wolfram.com/language/RLink/ref/REvaluate.html}, note=[Accessed: 22-June-2025 ]}

✖
@online{reference.wolfram_2024_revaluate, organization={Wolfram Research}, title={REvaluate}, year={2012}, url={https://reference.wolfram.com/language/RLink/ref/REvaluate.html}, note=[Accessed: 22-June-2025 ]}